In this article, we have discussed the basic knowledge to calculate sensitivity, specificity, positive predictive value and negative predictive value. We have discussed the advantage and limitations of these measures and have provided how we should use these measures in our day-to-day clinical practice. We also have illustrated how to calculate sensitivity and specificity while combining two tests and how to use these results for our patients in day-to-day practice.

An evaluation of medical college departments of ophthalmology in India and change following provision of modern instrumentation and trainingRavi Thomas, Mangat DograJanuary-February 2008, 56(1):9-16DOI:10.4103/0301-4738.37589 PMID:18158398

Aim: To evaluate teaching and practice in medical college ophthalmology departments in a representative Indian state and changes following provision of modern instrumentation and training.
Study Type: Prospective qualitative study.
Materials and Methods: Teaching and practice in all medical colleges in the state assessed on two separate occasions by external evaluators. Preferred criteria for training and care were pre-specified. Methodology included site visits to document functioning and conduct interviews. Assessments included resident teaching, use of instrumentation provided specifically for training and standard of eye care. The first evaluation (1998) was followed by provision of modern instrumentation and training on two separate occasions, estimated at Rupees 34 crores. The follow-up evaluation in 2006 used the same methodology as the first.
Results: Eight departments were evaluated on the first occasion; there were 11 at the second. On the first assessment, none of the programs met the criteria for training or care. Following the provision of modern instrumentation and training, intraocular lens usage increased dramatically; but the overall situation remained essentially unchanged in the 8 departments evaluated 8 years later. Routine comprehensive eye examination was neither taught nor practiced. Individually supervised surgical training using beam splitters was not practiced in any program; neither was modern management of complications or its teaching. Phacoemulsification was not taught, and residents were not confident of setting up practice. Instruments provided specifically for training were not used for that purpose. Students reported that theoretical teaching was good.
Conclusions: Drastic changes in training, patient care and accountability are needed in most medical college ophthalmology departments.

Context: There is growing body of evidence that use of computers can adversely affect the visual health. Considering the rising number of computer users in India, computer-related asthenopia might take an epidemic form. In view of that, this study was undertaken to find out the magnitude of asthenopia in computer operators and its relationship with various personal and workplace factors.
Aims: To study the prevalence of asthenopia among computer operators and its association with various epidemiological factors.
Settings and Design: Community-based cross-sectional study of 419 subjects who work on computer for varying period of time.
Materials and Methods: Four hundred forty computer operators working in different institutes were selected randomly. Twenty-one did not participate in the study, making the nonresponse rate 4.8%. Rest of the subjects (n = 419) were asked to fill a pre-tested questionnaire, after obtaining their verbal consent. Other relevant information was obtained by personal interview and inspection of workstation.
Statistical Analysis Used: Simple proportions and Chi-square test.
Results: Among the 419 subjects studied, 194 (46.3%) suffered from asthenopia during or after work on computer. Marginally higher proportion of asthenopia was noted in females compared to males. Occurrence of asthenopia was significantly associated with age of starting use of computer, presence of refractive error, viewing distance, level of top of the computer screen with respect to eyes, use of antiglare screen and adjustment of contrast and brightness of monitor screen.
Conclusions: Prevalence of asthenopia was noted to be quite high among computer operators, particularly in those who started its use at an early age. Individual as well as work-related factors were found to be predictive of asthenopia.

Topical and/or intracameral administration of anticholinergic and/or sympathomimetic mydriatic agents which are usually used for pupillary dilation during cataract surgery, have some disadvantages such as slow onset of dilation and adverse ocular and systemic effects. We evaluated intracameral injection of preservative-free 1% lidocaine without using any preoperative or intraoperative mydriatics to induce pupil dilation in 31 consecutive eyes scheduled for phacoemulsification cataract extraction and intraocular lens implantation. Pupil diameter was measured before and 90 sec after intracameral lidocaine injection. After intracameral lidocaine injection, the mean pupil diameter was significantly greater than the baseline measurement (P<0.001). No additional mydriatics were needed up to the end of the operations. Intracameral preservative-free lidocaine 1% has a rapid and effective mydriasis that could be a safe alternative to topical and intracameral mydriatics in phacoemulsification.

Dengue is known to affect the posterior segment of the eye, with a range of hemorrhagic and inflammatory sequelae. A 28-year-old lady convalescing from dengue fever complained of unilateral blurring of inferior visual field. She was evaluated clinically and with fluorescein angiography. Her best-corrected visual acuity was 20/20 bilaterally. Fundus examination revealed a branch retinal artery occlusion in the right eye. Fluorescein angiogram confirmed the clinical diagnosis; and also revealed a late staining and leakage from the affected arterial segment. The patient maintained status quo over a follow-up of six months. We report a major vascular occlusion complicating classic dengue fever even in the absence of severe systemic manifestations.

Purpose: A community-based survey was conducted in Rajnandangaon district of Chhattisgarh state of central India in 2001 to assess the prevalence of glaucoma in the age group of =35 years.
Design: Community-based cross-sectional survey
Materials and Methods: Ophthalmologists measured ocular pressure using Perkins applanation tonometer. Best corrected visual acuity was checked by ETDRS chart. After dilating the pupil the fundus was examined. A sketch diagram was drawn to note glaucomatous changes in optic disc and the surrounding retina. The field of vision was tested on Bjerrum screen. Gonioscopy was performed to determine type of glaucoma. Persons and their relatives were interviewed to find out risk factors and glaucoma treatment in the past.
Results: Seven thousand four hundred and thirty-eight (87.3%) persons were examined. The age-sex standardized prevalence of glaucoma was 3.68% (95% CI 3.27 to 4.07). Gender variation of glaucoma was not significant. [OR = 1.13 (CI 95% 0.88 to 1.44)] Glaucoma varied significantly by age groups. (χ2 = 48.2, degree of freedom = 3 P <0.001) Among those patients diagnosed to suffer from glaucoma, the proportion of open angle, closed angle, secondary glaucoma, ocular hypertension and glaucoma suspects was 13.1%, 21.2%, 21.2%, 14.5% and 30% respectively. Different types of visual disabilities were associated with glaucoma. However, unilateral blindness in glaucoma was unusual. Twenty-five per cent of the glaucoma cases were detected for the first time during the survey.
Conclusions: The prevalence of glaucoma was high and the angle closure type was more compared to the open angle glaucoma.

Background: Many eyes with proliferative diabetic retinopathy (PDR) require vitreous surgery despite complete regression of new vessels with pan retinal laser photocoagulation (PRP). Changes in the vitreous caused by diabetes mellitus and diabetic retinopathy may continue to progress independent of laser regressed status of retinopathy. Diabetic vitreopathy can be an independent manifestation of the disease process.
Aim: To examine this concept by studying the long-term behavior of the vitreous in cases of PDR regressed with PRP.
Materials and Methods: Seventy-four eyes with pure PDR (without clinically evident vitreous traction) showing fundus fluorescein angiography (FFA) proven regression of new vessels following PRP were retrospectively studied out of a total of 1380 eyes photocoagulated between March 2001 and September 2006 for PDR of varying severity. Follow-up was available from one to four years.
Results: Twenty-three percent of eyes showing FFA-proven regression of new vessels with laser required to undergo surgery for indications produced by vitreous traction such as recurrent vitreous hemorrhage, tractional retinal detachment, secondary rhegmatogenous retinal detachment and tractional macular edema within one to four years.
Conclusion: Vitreous changes continued to progress despite regression of PDR in many diabetics. We identifies this as "clinical diabetic vitreopathy" and propose an expanded classification for diabetic retinopathy to signify these changes and to redefine the indications for surgery.

Minimally invasive "keyhole" surgery performed using endoscopic visualization is increasing in popularity and is being used by almost all surgical subspecialties. Within ophthalmology, however, endoscopic surgery is not commonly performed and there is little literature on the use of the endoscope in orbital surgery. Transorbital use of the endoscope can greatly aid in visualizing orbital roof lesions and minimizing the need for bone removal. The endoscope is also useful during decompression procedures and as a teaching aid to train orbital surgeons.
In this article, we review the history of endoscopic orbital surgery and provide an overview of the technique and describe situations where the endoscope can act as a useful adjunct to orbital surgery.

Aim: To study the indications, technique and diagnostic utility of helical computed tomographic dacryocystography (CTDCG).
Materials and Methods: Retrospective analysis of 13 patients who underwent CTDCG with subsequent surgical intervention, during the period January 2003 to December 2005, was done. Axial plain computed tomography (CT) scan was performed, followed by administration of water-soluble contrast in the conjunctival cul de sac or by cannulation of the lacrimal passages. Thin-slice helical CT with two-dimensional (2D) and three-dimensional (3D) coronal and sagittal reformation was done.
Results: Four patients were males and 9 were females. Age range was 5 to 62 years. Seven patients presented with watering and 6 patients with a medial canthal mass. Three patients had history of trauma. CTDCG was performed by instillation technique in 10 patients and by cannulation in 3 patients. CTDCG showed mass lesion displacing the sac in 5 cases, nasolacrimal duct obstruction in 6 cases and mucocele in 2 cases. Based on the findings on CTDCG, 5 patients underwent mass excision, 7 underwent dacryocystorhinostomy and 1 patient underwent primary silicone tube intubation.
Conclusion: Helical CTDCG is a safe and useful diagnostic tool for the lacrimal surgeon. Instillation technique is a physiological and convenient method, and cannulation is needed only in cases where adequate visualization is not achieved.

Metastatic tumor is the most common uveal malignancy. However, choroidal metastasis from a salivary gland neoplasm is extremely rare. We report a case of bilateral, multifocal choroidal metastasis from carcinoma of the submandibular gland.

Human ocular infestation by live filarial worm is a rare occurrence and has been reported mostly form South-East Asia. It involves the eyelids, conjunctiva, cornea, anterior chamber and uvea. No case of intravitreal Brugian microfilaria / adult worm has been found by Medline search. Here we report a case of live intravitreal adult Brugian filaria, where the parasite was successfully removed by pars plana vitrectomy. Identification of the worm was done by light microscopy and confirmed by immuno chromatographic test.

In this case report, we describe the rare occurrence of bilateral conjunctival retention cysts in a child with Stevens-Johnson syndrome. The case was managed conservatively as there were no functional or cosmetic problems.

A 31-year-old man with high axial myopia and strabismus fixus convergens underwent bilateral refractive lens exchange followed by a squint surgery (bilateral superior partial Jensen's procedure and medial rectus recession). After one year he presented with traumatic anterior dislocation of the sulcus fixated posterior chamber polymethyl methacrylate lens. The lens was dialed back into the ciliary sulcus without any complications. This case highlights the importance of implanting an intraocular lens (IOL) in-the-bag. If the IOL needs to be implanted in the sulcus, a larger diameter of the IOL with larger optic size and overall length is desirable, especially in highly myopic eyes.

New molecular biological technique of Polymerase Chain Reaction (PCR) based Restriction Fragment Length Polymorphism (RFLP) can identify the species from paraffin-embedded tissue section. We demonstrated Aspergillus fumigatus fungus by PCR-based RFLP technique from paraffin section of an eyeball of an eight-month-old child removed for endogenous endophthalmitis.

Purpose: To evaluate the subjective and objective cyclodeviational changes following different weakening procedures on superior and inferior oblique muscles
Design: Comparative case series
Materials and Methods: In a prospective institution based study, 16 cases of A pattern horizontal strabismus having superior oblique overaction were randomized to superior oblique weakening procedures: either silicon expander or translational-recession. Similarly, 20 cases of V pattern horizontal strabismus with inferior oblique overaction were randomized for inferior oblique weakening procedures: either 10 mm Fink's recession or modified Elliot and Nankin's anteropositioning. Cyclodeviation was assessed subjectively with the synoptophore and objectively using the fundus photograph before surgery and 3 months postoperatively. Change in cyclodeviation was measured by subjective and objective methods. The index of surgical effect (ISE) was defined as the net torsional change postoperatively.
Results: The difference between the extorsional change induced by the two superior oblique procedures, silicone expander (-6°) and translational recession (-11.3°), was statistically significant (P=0.001). Translational recession caused more extorsional change (ISE=296%) than silicone expander surgery (ISE=107%). The two inferior oblique weakening procedures, Fink's recession (+2.5°) and modified Elliot and Nankin's anteropositioning (+4.7°) produced equitable amount of intorsional shift with no statistical difference (P=0.93). Objective measurements were significantly more than the subjective measurements.
Conclusions: Different weakening procedures on oblique muscles produce different changes in cyclodeviation, which persists even up to 3 months. Subjective cyclodeviation is less than the objective measurements indicating partial compensation by sensorial adaptations.

Congenital anomalies of the lens include a wide range from lens coloboma to primary aphakia and doubling of lens. There have been few case reports of double lens; the etiology suggested is metaplastic changes in the surface ectoderm that leads to formation of two lens vesicles and hence resulting in double lens. We report a case with bilobed lens, which raises the possibility of explaining the etiology of double lens.

We report an atypical presentation of non-Hodgkin lymphoma (NHL) in a child aged 18 months who presented with rapidly progressive bilateral proptosis. Computerized search using Medline did not reveal a similar presentation of NHL in such a young child. It stresses the need for an early histopathological study including immunohistochemistry and demonstrates the dramatic local response to combined radiotherapy and chemotherapy even in advanced stages without any ocular side-effects.